I am looking for the SecureVNCPlugin64.dsm. Where do I find this, please?

I found the plugin-SecureVNCPlugin64.dsm -but I cannot get the program to work now. My computer is the Client computer and it has Windows 10 Home Edition. The server computer has Windows 7 Home Edition.

I am getting an error message when I try to log in.

"Handshake response lacked client authentication key."

What is the "Client Authentication Key" that this error message is referring too, please?